The length of time over which medical dressings may remain in place over wounds may be limited by many factors. Among the factors that may limit the usable life of a medical dressing is the accumulation of fluids within the wound. Some medical dressings have incorporated absorbent materials to increase the time over which the medical dressings may remain in place over wounds. For example, absorbent materials such as hydrocolloids, foams, hydrogels, nonwovens (such as alginates and carboxymethylcelluloses), and combinations thereof have been used to increase the useful life of medical dressings.
Other approaches to increasing useful life of medical dressings have included the use of negative pressure wound therapy in which fluids are removed from the beneath the wound dressings without requiring removal of the dressings from the patient. Dressings adapted for delivery of negative pressure wound therapy (such as those described in, e.g., U.S. Pat. Nos. 4,969,880; 5,261,893; 5,527,293; and 6,071,267 (all to Zamierowski)) often have constructions that can compromise the sterility of the wound over which they are placed. These products often require a tube or wound drain that is introduced either through a multi-piece dressing or under a single piece dressing. In either case, it is difficult (if not impossible) to obtain a good seal between the tube or wound drain and, during treatment, air can leak into the wound. That air can carry contamination into the wound and/or impair the effectiveness of the pressure-based therapy.
U.S. Pat. No. 5,478,333 describes a wound dressing for chest wounds with a one-way valve. The dressing may also be used in conjunction with a “suction producing device” that is inserted into the one-way valve. Negative pressure is applied by inserting the suction-producing device through the valve.